Fluctuations in intraocular pressure increase the trabecular meshwork extracellular matrix

Area of Science:

• Ocular Physiology
• Biomechanical Stress
• Trabecular Meshwork (TM) Research

Background:

• Trabecular meshwork (TM) tissue is subject to dynamic stress from intraocular pressure (IOP).
• The biomechanical effects of IOP fluctuations on TM tissue remain largely unanalyzed.
• Understanding these effects is crucial for ocular health and disease research.

Purpose of the Study:

• To develop an animal model simulating fluctuating intraocular pressure (IOP).
• To evaluate the impact of dynamic IOP stress on the trabecular meshwork (TM) tissue.
• To investigate molecular and morphological changes in the TM due to IOP fluctuations.

Main Methods:

• Adult Sprague-Dawley rats were subjected to daily cyclic IOP fluctuations (5-45 mmHg at 1/60 Hz) for 30 minutes.
• Control eyes remained untreated.
• Hematoxylin-eosin staining and immunohistochemistry were used to assess TM morphology, cell density, and expression of α-smooth muscle actin (α-SMA), laminin (LA), and fibronectin (FN).

Main Results:

• TM thickness remained unchanged, but TM density significantly increased after several weeks of IOP fluctuation.
• Expression of α-SMA, LA, and FN was detected and significantly increased in the TM of treated eyes.
• No significant ganglion cell loss was observed, and IOP levels were comparable between treated and control eyes, with a slight trend of increase on day 22.

Conclusions:

• Significant fluctuations in IOP can induce pathological changes in the TM.
• These changes include increased TM density and elevated synthesis of α-SMA, LA, and FN.
• The developed animal model provides insights into the biomechanical effects of IOP variability on ocular tissues.